Cubert J. Farnsworth is the clone of Professor Hubert J. Farnsworth, but he takes on the role of his son. The DNA used to clone him was scraped from a growth on the Professor's back in 2989, and this is the day that is celebrated in lieu of an actual birthday. His nose is flattened due to the Professor accidentally leaving him in one of his earlier cloning tubes for too long.

He is the sole heir to Planet Express and Professor Farnsworth fortune, as he is Professor Farnsworth's closest living relative. He spends most of his time within the Planet Express building with the Planet Express crew, and during his first appearance, A Clone of My Own, appeared to criticize everything. He seems highly intelligent, but in reality he is usually just pointing out the logical flaws in the behaviors and actions of others, and the ways in which his father's inventions defy the laws of science.

Because he is Professor Farnsworth's clone, he is technically his identical-twin brothеr, but due to being much younger Farnsworth treats him as a son, and refers to him as such. According to Bender, Cubert is legally the same person as the Professor ("Overclockwise").

In "The Late Phillip J. Fry", he was married to Leela after Fry vanished in the forwards time machine. Only because Cubert reminded Leela of Fry.